Electric detonator



6. DE BENEDETTI 2,192,542

ELECTRIC DETONATOR Filed June 3. 1937 Fig. 3

. 1 a5 5 5A I 222 fenwlv Patented Mar. 5,, 1

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ELECTRIC DIETONATB Giacomo De Benedetti, Turin, Etaly Application]! 4 Claims.

This invention relates to an electric detonator for mines or low speed projectiles provided in the body of the mine or projectile and in which the igniting spark is supplied by an electric our- 5 rent generator driven by a spring motor provided with means for winding it. This spring mechanism is normally kept from unwinding, but a detent device is released upon mechanical shock to drive the generator.

The various objects and features of the invention will be apparent to those skilled in the art upon a consideration of the accompanying drawing and the following description wherein several exemplary embodiments of the invention are disclosed.

In the drawing:

Figure l is a longitudinal axial section of the detonator part that is essential to the inventiin.

Figure 2 is a sectional view of the inside of the bottom part taken on line II--II of Fig. 1.

Figure 3 is a sectional view of a delay device and a Figure 4 is a top view thereof.

According to Figures 1 and 2, the spring motor and electric current generator are arranged in the body i, which is subdivided by the plate 2 into two superposed chambers. The top chamber contains the spring 3, one of the ends whereof is attached to the body i, while the other end is attached to a bush 6 loosely mounted on the shaft 5. The lower end of the bush 6 is formed with saw teeth meshing with 'assoclated teeth on a ring 8 secured on the shaft 5.

The shaft 5 passes through the lower portion of the body i and the permanent magnet 9 in the shape of a cylinder. Underneath ,the permanent magnet 9 the shaft 5 carries the coil it forming the rotor of the current generator, 40 while the stator is formed by the U-shaped pole pieces ll, E2 of the permanent magnet 9 merging with the two ends of the latter.

A pinion i3 is fixed to the lower end of the shaft 5 and meshes with the teeth id of a metal disc i5 having on one side a sector is of insulating material. A contact Ii formed by a terminal for the feed current wipes on this side of the disc. An end of the coil iii is electrically connected to the disc l5 through the shaft 5 and the pinion i3, and its other end is electrically connected to the second feed terminal i9 by means of a slip ring l9a. In its inoperative position the wiping contact I! engages the insulating sector it and the igniting circuit is 55 open. When the spring motor is released, ro-

June 3, 1937, Serial No. 146,305 in lltaiy June 3, 1936 tation of the disc' He brings the conducting portion of the disc on the wiping contact i1 and the igniting circuit is closed. The transmission ratio between the shaft 5 and disc i5 is chosen in such manner that the igniting circuit is closed during unwinding of thespring 3.

The arrangement of this circuit breaking device is more particularly advantageous in submarine mines and the like having a plurality of detonators, the igniting circuits of which act upon one charge. It has been found that on impact of one of these detonators, a portion of the current generated is lost by induction in the lines of the other detonators, if these circuits are closed. This reduces the current available for forming the igniting spark and makes ignition uncertain, unless powerful current generators are employed, which would objectionably increase the size of the unit and cost of the detonator. The use of the breaking device it, i? obviates this drawback, as there are no closed circuits of the inoperative detonators.

The spring 8 is wound by means of a key fitted on the end 20 of the shaft 5.

The ratchet wheel 1 is mounted outside the body i at the top end-of the shaft 5 and a ratchet pawl B cooperates with said wheel to keep the spring from unwinding. The pawl 8 may be released by a sudden mechanical shock and the spring 3 unwinds to rotate the rotor of the current generator.

The bushing i is coupled to the ring 6 by means of saw teeth so that the rotor may revolve after the spring 3 is fully unwound thus avoiding rupture of the spring as 'a result of the inertia of the revolving rotor.

In the construction shown in Figure l, the arrangement of the rotor, stator and spring motor in alignment is more particularly advantageous, for it permits of reducing the detcnator in width. I

When it is desired to produce ignition only a certain time after impact of the projectile, as is frequent in impact detonators, the detonator is provided with a delay device, for instance of the type shown in Figures 3 and 4. In this case the top portion of the body i carries a box 2! for the spring 3 having a toothed rim 22 which meshes with the pinion 23 of a winding-up device mounted on the shaft 24 projecting outwardly and carrying at its outer end the handle 25. The pawl it prevents backward rotation of the pinion 23 and box 2| to which the outer end of the spring is attached.

ihe other spring end is attached to the shaft '27 carrying the ratchet wheel 28 engaging the and the pawl 29 is released and the spring motor is allowed to unwind.

The mechanism cannot attain at once the speed required for igniting on account of the provision of the delay device. The delay device shown by way of example consists chiefiy of a screw 36 on which a bush 35 fixed to the cover of the body 9 is screwed.

The screw 36 carries a pinion 36 having teeth of a substantial length. The pinion 36$ meshes with a toothed wheel 37 mounted on the shaft 277 of the spring motor. A toothed wheel 38 is fired to the screw 36 and meshes with a pinion controlling a damping wing 62.

As the spring motor begins to unwind, the screw 34 is set in rotation by the gears 3'! and 36 and is screwed up into the bush As a result of this rotation, the screw is raised and carries with it the pinion 36. This rotational movement is braked by the damping wing as long as the pinion 3B is in engagement with the toothed wheel 3?. When the pinion 36 no longer meshes with the toothed wheel 31, the spring motor is released and promptly reaches its operating speed. The duration of damping and,

. consequently, the ignition delay depend upon the starting position of the pinion 36 with respect to the level of the toothed wheel 31. It is thus possible to adjust the delay by varying the initial position of the pinion 36. For this purpose a milled button 40 is provided on the dial 4|, which is fixed to the upper end of the screw 34. I wish to be understood that I do not desire to be limited to the exact details of construction shown and described, for obvious modifications will occur to a person skilled in the art.

What I claim is: 1. A device for use in detonating an .explosive charge comprising, an electric generatonfor producing a spark, a spiral spring connected to said generator for driving the same, hand-operated means for winding the driving spring, detent means to keep'said spring from unwinding and automatically operable means for releasing saiddetent means and a delay device for delaying the formation of the spark during rotation of the generator, this delay device comprising a braking member, a gear transmission between said braking member and the current generator, and.

a nut and screw mechanism, one of the members of which is fixed and the other is coupled for rotation with one of the gears of said transmission in such manner as to bring it out of engagement after a certain time of rotation.

2. A device for use in detonating an explosive charge comprising, an electric generator for producing a spark, a spiral spring connected to said generator for driving the same, hand-operated means for winding the driving spring, detent means to keep said spring from unwinding and automatically operable means for releasing said detent means and a delay device for delaying the formation of the spark during rotation of the generator, this delay device comprising a braking member, a gear transmission between said braking member and the current generator, and a nut and screw mechanism, one of the members of which is fixed and the other is coupled for rotation with one of the gears of 1 said transmission in such manner as to bring it out of engagement after a certain time of rotation and hand-operated means for adjusting the initial position of the screw and nut mechanism and timing the delay action of said device.

3. A device for use in detonating an explosive charge comprising, an electric generator for producing a spark consisting 01' a stator constituted by a permanent magnet of cylindrical form, U-shaped pole pieces attached one at each end of said magnet and having their arms arranged at 90 to each other and extending from one end of said magnet, a rotor arranged between said projecting arms and a shaft for said rotor passing through an axial bore of said magnet, a spiral spring coaxially arranged on said magnet for driving said shaft, hand-operated means for winding said driving spring, detent means to keep said spring from. unwinding and means operable upon mechanical shock for releasing said detent means.

4. A device for use-in detonating an explosive charge comprising, a firing circuit, an electric generator for producing the spark current in said circuit, comprising a stator constituted by a permanent magnet of cylindrical form, U-shaped pole pieces attached at each end of said magnet and having their arms arranged at 90 ,t o each other and extending from the ends of v.s'aid magnet, a rotor arranged between said projecting arms and a shaft for said rotor passing through an axial bore of said magnet, a' spiral spring coaxially arranged on said magnet for driving said shaft, hand-operated means for winding said driving spring, detent means to keep said spring from unwinding, automatically operable means for releasing said detent means and a contact mechanism in said firing circuit and controlled by said shaft so that when the deviceis in its inoperative position it maintains said circuit open while and when the' spring unwinds to operate the generator, said contact mechanism closes said circuit and maintains itclosed as long as the driving spring is unwinding.

GIACOMO DE BENEDETTI. 

